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Re: Functions and arrays [message #7603 is a reply to message #7602]

Wed, 04 December 1996 00:00

rigby
Messages: 16
Registered: September 1995

Junior Member

In article 6ll@post.gsfc.nasa.gov, thompson@orpheus.nascom.nasa.gov (William Thompson) writes:
>
> I've just run into a serious limitation in the way IDL handles functions and
> arrays. I've always been aware that there was an ambiguity in the IDL syntax,
> ...
> It is my opinion that IDL should be tightened in its handling of arrays and
> functions. If a procedure contains a variable with a given name, then it
> should be unambiguous that one is referencing that variable, and not some
> function which happens to share the same name.
> ...
> William Thompson

Please complain directly to RSI about this! We ran into this about a year
ago, and were unable to get past the first level support folks telling us that
this was an inevitable consequence of IDL's weak typing.

We even gave them an example of how their own routines could be broken.
The routine poly.pro in $IDL_DIR/lib happens to use the name C for
one of its formal arguments:
FUNCTION POLY,X,C
If a user should compile a function C before POLY is compiled, he/she will
get the wrong answer from POLY. Silently.

IDL> .run
- function c, arg
- return, arg-1000
- end
Compiled module: C.
IDL> print, poly(1,[1,1])
Compiled module: POLY.
-1999 (should be 2).

There's no reasonable way to defend yourself against this either.
Are you supposed to examine the formal argument list of every routine you use??

---
Wayne Rigby
GE Corporate Research and Development
rigby@crd.ge.com

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[Message index]

		Re: Functions and arrays By: David R. Klassen on Sat, 07 December 1996 00:00
		Re: Functions and arrays By: Tim Patterson on Fri, 06 December 1996 00:00
		Re: Functions and arrays By: haimov on Fri, 06 December 1996 00:00
		Re: Functions and arrays By: steinhh on Fri, 06 December 1996 00:00
		Re: Functions and arrays By: greenwoodde on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: William Clodius on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: thompson on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: Mirko Vukovic on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: brian.jackel on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: Anonymous on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: llobet on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: Peter Mason on Thu, 05 December 1996 00:00
		Re: Functions and arrays By: thompson on Wed, 04 December 1996 00:00
		Re: Functions and arrays By: steinhh on Wed, 04 December 1996 00:00
		Re: Functions and arrays By: gunter on Wed, 04 December 1996 00:00
		Re: Functions and arrays By: rigby on Wed, 04 December 1996 00:00

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